A comparative study of agonistic behaviour in hairy-footed gerbils of the genus Gerbillurus (Shortridge, 1942)

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Abstract

Agonistic behaviour was investigated by means of staged
encounters in three species and two subspecies of
deserticolous rodents of the genus Gerbillurus
Indiviuals of the species G.paeba paeba, G.paeba exilis, G. tytonis, G. setzeri, and G. vallinus were used in
intraspecific and interspecific encounters. Intraspecific
territoriality was tested in animals of the same sex G.paeba paeba, G. tytonis, and G. setzeri
Analysis of agonistic behaviour permitted identification of
four groups of behaviours in most classes of intraspecific
encounters. These were "exploratory and solitary",
"aggressive", "submissive", and "sexual" behaviours.
Males of four species were less aggressive than females in
same-sex encounters, and were dominated by females in
different-sex encounters; the reverse was observed in G. setzeri.
Male G. tytonis and G. setzeri were more tolerant
of conspecifics in the territoriality apparatus than females
were.
In G. tytonis-G.p. paeba encounters a hierarchy emerged:
female G.. tytonis were most aggressive, followed by female G.p. paeba,
male G. tytonis, and finally male G.p. paeba.
In areas of syntopy, G. tytonis displace G.p. paeba
through aggressive interactions. A reduction in the level
of aggression was exihibited in G.p. paeba-G. setzeri and G. tytonis-G. interactions.
This result may reflect the phylogenetic divergence and selection of a different
habitat by G. setzeri. G. vallinus dominated G.p. paeba, a
result which may have been influenced by past experience and
body size, since these two species are syntopic and G. vallinus
is larger than G.p. paeba.
Cluster analysis of behaviour profiles of different species
and sexes revealed two groups, which agree partially with
the karyology of the genus. G.p. paeba and G. tytonis formed
one cluster, while G. setzeri and female G.p. exilis formed
a second group. Male G.p. exilis and G. vallinus were less
closely related to both groups. It is suggested that
several stages in the process of speciation are represented
in species of this genus . A range of social types is
exhibited from solitary (G.p. paeba and G. tytonis) through semi-tolerant (G. setzeri and G. tytonis) through semi-tolerant (G. setzeri and female G.p. exilis)
to tolerant
(male G.p. exilis and G. vallinus). Habitat has a strong
influence on social type.